Compressor liquid return protection

ABSTRACT

For restraining the flow of refrigerant liquid into the oil sump of a refrigerant compressor, a partition extends across the interior of the compressor in contact with the crankcase of the latter, above the sump. The partition has upwardly extending standpipes for permitting the flow of gas from the sump, and has small oil drain holes. Heat from the crankcase and the cylinders of the compressor evaporates refrigerant liquid which has accumulated on the partition.

United States Patent 1191 Ayling Oct. 16, 1973 COMPRESSOR LIQUID RETURN 2,752,088 6/1956 Borgerd 417/372 x PROTECTION 3,073,515 1/1963 Neubauer 3,229,901 l/l966 Parker 417/372 [75] Inventor: Robert W. Ayling, Bristol, Va.

[73] Assignee: Sundstrand Corporation, Rockford, Primary Examiner-William L. Freeh 111. At10rneyRobert T. Palmer [22] Filed: Apr. 14, 1972 211 App]. N0.2 244,212 [57] ABSTRACT For restraining the flow of refrigerant liquid into the [52] U S Cl 417/372 oil sump of a refrigerant compressor, a partition ex- [51] In: CL 39/14 tends across the interior of the compressor in contact [58] Fie'ld with the crankcase of the latter, above the sump. The

372 partition has upwardly extending standpipes for permitting the flow of gas from the sump, and has small [56] References Cited oil drain holes. Heat from the crankcase and the cylinders of the compressor evaporates refrigerant liquid UNITED STATES PATENTS which has accumulated on the partition. 3,486,687 12/1969 Ayling 417/312 9 2,152,056 3/1939 Kenney 417/372 1 Claim, 2 Drawing Figures COMPRESSOR LIQUID RETURN PROTECTION BACKGROUND OF THE INVENTION Hermetic refrigerant compressors such as are disclosed in my U. S. Pat. Nos. 3,171,588; 3,259,307 and 3,486,687 have oil sumps in their bottoms, and have suction gas tubes with outlets in their upper portions. Oil and refrigerant liquid in the suction gas flow into the oil sumps. The refrigerant liquid that flows into the oil sumps may so greatly dilute the oil that the bearings of the compressors may become starved with the result that the compressors may fail. My previously mentioned U.S. Pat. No. 3,486,687 discloses a cylindrical inner shell supported at its bottom above an oil sump by' a crankcase of a compressor, and extending in contact with the cylinder heads and the muffler of the compressor. Refrigerant liquid in the suction gas flows into the inner shell which acts as an accumulator, the heat from the crankcase, the cylinder heads and the muffler evaporating the refrigerant liquid within the inner shell. A small hole in the bottom of the inner shell permits oil to drain into the oil su'mp. The present invention is an improvement on that of the US. Pat. No. 3,486,687.

SUMMARY OF THE INVENTION A hermetic refrigerant compressor has a lower shell with an oil sump in its bottom, and has a suction gas inlet in its upper portion. Oil and refrigerant liquid in the suction gas flow with the latter into the compressor. The crankcase of the compressor is supported on a plate supported by the lower shell and extending across the interior of the latter. Standpipes which connect with the space between the oil level in the sump and the plate, extend from the plate upwardly between the compressor cylinders. The standpipes serve to equalize pressures above the level of the liquid accumulating on the plate, and above the oil level in the sump, and to vent gas from the sump. There are small oil drain holes in the plate which are too small to permit appreciable quantities of refrigerant liquid to flow into the sump. Liquid entering with the suction gas builds up to such a level on the plate that it directly contacts the crankcase and the cylinders, heat from which evaporates refrigerant liquid which otherwise would flow into the oil sump to dilute the oil therein.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l of the drawings is a side elevation, partially in section, of a refrigerant compressor embodying this invention, and

FIG. 2 of the drawings is a simplified plan view looking downwardly on the compressor of FIG. I, with the upper shell, the motor housing, and the motor removed, and with the muffler, tubing, bolts and wiring omitted, the purpose of FIG. 2 being to show the locations of all of the compressor cylinders, and the locations with respect thereto of all of the standpipes and oil drain holes.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawings, a domed upper shell around the upper portion of motor compartment 11 is attached to an intermediate shell 12 which is attached to a lower shell 13 extending around the lower portion of the assembly. The lower shell 13 forms an oil sump 15. An electric motor 16 has a rotor 17 attached by a key 19 to a vertically extending crankshaft 20. A stator 18 extends aroundthe rotor 17. A motor housing 22 extends over and around the motor 16. An upper bearing housing 24 around bearings 25 and 26 for the crankshaft 20 is formed to compressor cylinders 30, 31 and 32, and to crankcase 33. A lower bearing housing 35 within the oil sump 15 is bolted to the crankcase 33, and has a bearing 36 around the lower portion of the crankshaft 20. The housing 35 has an oil inlet passage extending through its bottom. The crankshaft 20 has a crankpin 37 on which eccentric strap 38 is journaled. The strap 38 is attached to piston 40 operating within the cylinder 30. Valve plate 46 at the top of the cylinder 30 is held in place by cylinder head 47. The cylinders 31 and 32 are similar to the cylinder 30, and have cylinder heads 48 and 49 respectively. The cylinder heads 47, 48 and 49 are connected by discharge gas tubes 50, 51 and 55 respectively, to a conventional muffler 52, the outlet of which connects with outlet tube 53. A suction gas tube 54 connects through the upper shell 10 with the motor compartment 11. The crankshaft 20 has thereon below the eccentric strap 38, a conventional counterweight 59.

Oil is pumped by a conventional pumping system (not shown) from the sump 15 to the bearings 25, 26 and 36.

The structure described in the foregoing with reference to the drawings is conventional, and is essentially that disclosed in my previously mentioned patent No. 3,259,307.

This invention adds a circular plate 56 with a central circular opening 57 extending around and in contact with the lower bearing housing 35, and on which the crankcase 33 rests. The lower shell 13 has an inwardly offset shoulder 58 on which the outer edge of the plate 56 is supported. The internal assembly of the compressor is therefore supported by the plate 56 and the lower shell 13. This invention also adds on the plate 56, a standpipe 60 between the cylinders 31 and 32, a standpipe 61 between the cylinders 31 and 30, and a standpipe 62 between the cylinders 30 and 32. These standpipes connect with the space between the plate 56 and the oil level in the sump 15, and extend upwardly from the plate 56 between pairs of cylinders. The plate 56 has a small oil drain hole 65 therein adjacent to the standpipe 60, has a small oil drain hole 66 therein adjacent to the standpipe 61, and has a small oil drain hole 67 therein adjacent to the standpipe 62. More or fewer standpipes and oil drain holes could be used.

In operation, oil and refrigerant liquid entering the compressor through the suction gas tube 54 fall onto the plate 56 and build up to a level adjacent to the tops of the standpipes 60, 61 and 62 which are similar, the liquid at that level directly contacting the crankcase 33 and the cylinders 30, 31 and 32. Heat from the crankcase and the cylinders evaporates refrigerant liquid. Oil flows through the small oil drain holes 65, 66 and 67. The oil drain holes are too small to permit the flow of a substantial amount of refrigerant liquid into the oil sump. The standpipes equalize the pressures above the oil level in the oil sump and above the liquid level on the plate 56, and vent gas from the oil sump into the space above the standpipes.

The advantages of the present invention over that of my previously mentioned US. Pat. No. 3,486,687 are that the plate which forms the bottom of the liquid reservoir also supports the internal compressor assembly;

the capacity for liquid retention is greater since the reservoir extends to the surrounding shell; no bypassing of the liquid is possible since the outer boundry of the reservoir is the surrounding shell; at ambients above the saturated suction temperature, heat from the surrounding air is transmitted through the compressor shell to the liquid to be evaporated, and is simplier, less expensive, and easier to assemble.

l claim:

1. In a refrigerant compressor having shell means with a closed bottom, the lower portion of said shell means above said bottom and said bottom forming an oil sump, a crankcase above said sump, cylinders above said crankcase and joined thereto, a crankshaft having its lower portion within said sunp and extending upwardly therefrom, a bearing around said lower portion of said crankshaft, and a bearing housing having its lower portion within said sump, said bearing housing being joined to said crankcase, said housing having a bottom with an oil inlet passage extending therethrough, said shell means extending around and spaced outwardly from said cylinders and said crankcase, and having a suction gas connection extending through its upper portion above said cylinders, the improvement comprising: i

a plate having an opening around the top of said housing and in contact with said top of said housing around said opening,

the outer edge of said plate contacting the inner surface of said shell means,

said plate being-supported at said edge by said shell means,

the upper surface of said plate contacting the lower surface ofsaid crankcase,

said crankcase being supported on said plate, and

hollow standpipe means on said plate extending upwardly above said plate, and connecting through said plate with said sump,

said plate having small oil drain hole means extending therethrough,

said plate sealing said sump from the space within said shell means above said plate except that said standpipe means equalizes pressures above and below said plate, and that said drain hole means permits oil and refrigerant to flow from said space into said sump. 

1. In a refrigerant compressor having shell means with a closed bottom, the lower portion of said shell means above said bottom and said bottom forming an oil sump, a crankcase above said sump, cylinders above said crankcase and joined thereto, a crankshaft having its lower portion within said sunp and extending upwardly therefrom, a bearing around said lower portion of said crankshaft, and a bearing housing having its lower portion within said sump, said bearing housing being joined to said crankcase, said housing having a bottom with an oil inlet passage extending therethrough, said shell means extending around and spaced outwardly from said cylinders and said crankcase, and having a suction gas connection extending through its upper portion above said cylinders, the improvement comprising: a plate having an opening around the top of said housing and in contact with said top of said housing around said opening, the outer edge of said plate contacting the inner surface of said shell means, said plate being supported at said edge by said shell means, the upper surface of said plate contacting the lower surface of said crankcase, said crankcase being supported on said plate, and hollow standpipe means on said plate extending upwardly above said plate, and connecting through said plate with said sump, said plate having small oil drain hole means extending therethrough, said plate sealing said sump from the space within said shell means above said plate except that said standpipe means equalizes pressures above and below said plate, and that said drain hole means permits oil and refrigerant to flow from said space into said sump. 